Coating compositions for use with an overcoated photoresist

ABSTRACT

Organic coating composition are provided including antireflective coating compositions that can reduce reflection of exposing radiation from a substrate back into an overcoated photoresist layer and/or function as a planarizing or via-fill layer. Preferred organic coating compositions of the invention comprise one or more resins that can harden upon thermal treatment without generation of a cleavage product. Particularly preferred organic coating compositions of the invention comprise one or more components that comprise anhydride and hydroxy moieties.

This application is a continuation application of U.S. application Ser.No. 11/712,160, filed Feb. 28, 2006 which claims the benefit of U.S.provisional application 60/777,788 filed Feb. 28, 2006.

The present invention relates to compositions (including antireflectivecoating compositions or “ARCs”) that can reduce reflection of exposingradiation from a substrate back into an overcoated photoresist layerand/or function as a planarizing or via-fill layer. More particularly,the invention relates to organic coating compositions, particularlyantireflective coating compositions, that comprise one or more resinsthat can harden upon thermal treatment, without use of a separatecrosslinker component.

Photoresists are photosensitive films used for the transfer of images toa substrate. A coating layer of a photoresist is formed on a substrateand the photoresist layer is then exposed through a photomask to asource of activating radiation. The photomask has areas that are opaqueto activating radiation and other areas that are transparent toactivating radiation. Exposure to activating radiation provides aphotoinduced or chemical transformation of the photoresist coating tothereby transfer the pattern of the photomask to the photoresist-coatedsubstrate. Following exposure, the photoresist is developed to provide arelief image that permits selective processing of a substrate.

A major use of photoresists is in semiconductor manufacture where anobject is to convert a highly polished semiconductor slice, such assilicon or gallium arsenide, into a complex matrix of electronconducting paths, preferably of micron or submicron geometry, thatperform circuit functions. Proper photoresist processing is a key toattaining this object. While there is a strong interdependency among thevarious photoresist processing steps, exposure is believed to be one ofthe most important steps in attaining high resolution photoresistimages. Reflection of activating radiation used to expose a photoresistoften poses limits on resolution of the image patterned in thephotoresist layer. Reflection of radiation from thesubstrate/photoresist interface can produce spatial variations in theradiation intensity in the photoresist, resulting in non-uniformphotoresist linewidth upon development. Radiation also can scatter fromthe substrate/photoresist interface into regions of the photoresistwhere exposure is non intended, again resulting in linewidth variations.The amount of scattering and reflection will typically vary from regionto region, resulting in further linewidth non-uniformity. Variations insubstrate topography also can give rise to resolution-limiting problems.

One approach used to reduce the problem of reflected radiation has beenthe use of a radiation absorbing layer interposed between the substratesurface and the photoresist coating layer. See U.S. Patent Publication2005/0112494 which reports antireflective compositions that contain acertain resin, a glycoluril crosslinking agent and an acid.

For many high performance lithographic applications, particularantireflective compositions are utilized in order to provide the desiredperformance properties, such as optimal absorption properties andcoating characteristics. Nevertheless, electronic device manufacturerscontinually seek increased resolution of a photoresist image patternedover antireflective coating layers and in turn demand ever-increasingperformance from an antireflective composition.

It thus would be desirable to have new antireflective compositions foruse with an overcoated photoresist.

We have now discovered new organic coating composition includingantireflective compositions (“ARCs”) for use with an overcoatedphotoresist layer. Preferred organic coating compositions and systems ofthe invention can provide enhanced lithographic results (e.g.,resolution) of an overcoated photoresist image.

More specifically, in one aspect, organic coating compositions,particularly antireflective compositions for use with an overcoatedphotoresist, are provided that comprise one or more resins that canharden upon thermal treatment without use of a separate crosslinkercomponent, including without use of previously employed crosslinkerssuch as amine-based materials (e.g. melamine, glycouril orbenzoquanamine) or epoxy materials.

In another aspect, organic coating compositions, particularlyantireflective compositions for use with an overcoated photoresist, areprovided that comprise one or more resins that comprise anhydride andhydroxy (e.g. alcohol) moieties.

Preferred compositions of this aspect of the invention can undergohardening upon thermal treatment without the use of any separatecrosslinker component, including without use of previously employedcrosslinkers such as amine-based materials (e.g. melamine, glycouril orbenzoquanamine) or epoxy materials. In such preferred compositions,anhydride and hydroxy moieties react to harden the composition.

In a yet further aspect of the invention, organic coating compositions,particularly antireflective compositions for use with an overcoatedphotoresist, are provided that comprise one or more components that canharden upon thermal treatment without the liberation of any volatilespecies, i.e. a group that is cleaved (covalent bond breakage) in acrosslinking reaction, particularly where the cleavage product has amolecular weight of 500, 400, 300, 200, or 100 or less.

In preferred embodiments, thermal treatment of a coating composition ofthe invention promotes an addition reaction of one or more compositioncomponents, e.g. an addition reaction between anhydride and alcoholgroups that may be present on one or more composition components such asa resin component. Exemplary alcohol moieties include e.g. alcohol (e.g.C₁ _(_) ₁₂alcohol), carboxy, and aromatic alcohols such as phenolics andnaphthols. Exemplary anhydride groups include e.g. maleic anhydride,itaconic anhydride, and succinic anhydride.

In a still further aspect, organic coating compositions, particularlyantireflective compositions for use with an overcoated photoresist, thatdo not contain, or are at least essentially free of, an added acid oracid generator compound (e.g. thermal acid generator compound and/orphotoacid generator compound).

Antireflective coating compositions of the invention preferably willcomprise a component that contains one or more chromophore groups thatcan effectively absorb exposure radiation employed to image anovercoated photoresist layer. Typical chromophore groups are aromaticgroups such as optionally substituted carbocyclic aryl groups includingoptionally substituted phenyl, anthracene and naphthyl. Forantireflective coating compositions that are used with an overcoatedphotoresist composition imaged at 248 nm, preferred chromophore groupsmay include optionally substituted anthracene and optionally substitutednaphthyl. For antireflective coating compositions that are used with anovercoated photoresist composition imaged at 193 nm, preferredchromophore groups may include optionally substituted phenyl.

Such chromophore groups may be incorporated into an antireflectivecoating composition of the invention through a variety of approaches.Preferred compositions may comprise a resin component which comprisesone or more resins that comprise one or more chromophore groups such asoptionally substituted carbocyclic aryl groups that may be pendant orintegral to a resin backbone. Alternatively or in addition to such useof an absorbing resin, the antireflective composition may comprise afurther component such as one or more non-polymeric dye compounds thatcomprise such chromophore groups, e.g. a small molecule (e.g. MW lessthan about 1000 or 500) that contains one or more chromophore moieties,such as one or more optionally substituted phenyl, optionallysubstituted anthracene or optionally substituted naphthyl groups.

Preferably, coating compositions of the invention can be cured throughthermal treatment of the composition coating layer. Exemplary thermalcure conditions include treatment of a composition coating layer at 150°C. or more for 30 seconds or more.

For use as an antireflective coating composition, as well as otherapplications such as via-fill, preferably the composition is cured priorto applying a photoresist composition layer over the composition layer.

Coating compositions of the invention are typically formulated andapplied to a substrate as an organic solvent solution, suitably byspin-coating (i.e. a spin-on composition).

A variety of photoresists may be used in combination (i.e. overcoated)with a coating composition of the invention. Preferred photoresists foruse with the antireflective compositions of the invention arechemically-amplified resists, especially positive-acting photoresiststhat contain one or more photoacid generator compounds and a resincomponent that contains units that undergo a deblocking or cleavagereaction in the presence of photogenerated acid, such asphotoacid-labile ester, acetal, ketal or ether units. Negative-actingphotoresists also can be employed with coating compositions of theinvention, such as resists that crosslink (i.e. cure or harden) uponexposure to activating radiation. Preferred photoresists for use with acoating composition of the invention may be imaged with relativelyshort-wavelength radiation, e.g. radiation having a wavelength of lessthan 300 nm or less than 260 nm such as about 248 nm, or radiationhaving a wavelength of less than about 200 nm, such as 193 nm.

The invention further provides methods for forming a photoresist reliefimage an electronic devices as well as novel articles of manufacturecomprising substrates (such as a microelectronic wafer substrate) coatedwith a coating composition of the invention alone or in combination witha photoresist composition.

Other aspects of the invention are disclosed infra.

As discussed above, in one aspect, organic coating compositions,particularly antireflective compositions for use with an overcoatedphotoresist, are provided that comprise one or more components that canharden upon thermal treatment without the generation of any volatilespecies, i.e. a group that is cleaved (covalent bond breakage) in acrosslinking reaction, particularly where the cleavage product isrelatively low molecular weight such as a molecular weight of about 500,400, 300, 200 or 100 or less. In preferred embodiments, thermaltreatment promotes an addition reaction of one or more compositioncomponents, e.g. an addition reaction between anhydride and alcoholgroups that may be present on one or more composition components such asa resin component.

Preferred compositions of the invention can undergo hardening uponthermal treatment without the use of any separate crosslinker component,including such previously employed crosslinkers such as amine-basedmaterials (e.g. melamine, glycouril or benzoquanamine) or epoxymaterials.

Underlying Coating Compositions

Preferred coating compositions of the invention may suitably compriseone or more resins. The one or more resins may suitably comprise one ormore chromophore groups and one or more moieties that can result inhardening of a composition coating layer upon thermal treatment.

Preferred resins may be copolymers with two or more distinct repeatunits. Acrylate resins can be particularly suitable for manyapplications. Higher order resins also are preferred includingterpolymer (three distinct repeat units) and tetrapolymers (fourdistinct repeat units).

Coating compositions of the invention, particularly for reflectioncontrol applications, also may contain additional dye compounds thatabsorb radiation used to expose an overcoated photoresist layer. Otheroptional additives include surface leveling agents, for example, theleveling agent available under the tradename Silwet 7604 from UnionCarbide, or the surfactant FC 171 or FC 431 available from the 3MCompany.

Acrylate-based resins can be prepared by known methods, such aspolymerization (e.g. in the presence of a radical initiator) of one ormore acrylate monomers such as e.g. hydroxyethylmethylacrylate,hydroxyethylacrylate, methylmethacrylate, butylmethacrylatemethylanthracene methacrylate or other anthracene acrylateand the like. Other monomers including anhydrides such as maleicanhydride can be co-polymerized with acrylate monomers. For use inantireflective compositions, one or more co-polymerized monomers cancontain suitable chromophore groups, such as anthracene for use inantireflective coating compositions utilized with an overcoatedphotoresist imaged with 248 nm radiation, or phenyl for use in anantireflective coating composition imaged with 193 nm radiation. Seealso the examples which follow for suitable syntheses of resins usefulin coating compositions of the invention.

Particularly preferred coating compositions of the invention compriseone or more components that comprise anhydride and hydroxyl moieties. Insuch preferred compositions, anhydride and hydroxyl moieties may bepresent together on a single composition component such as a resin, e.g.by copolymerizing monomers that contain hydroxyl groups with anhydridemonomers. Alternatively, anhydride and hydroxyl moieties may be presenttogether on a distinct composition component such as distinct resins,e.g. where one resin comprises anhydride groups and a distinct resincomprises hydroxyl groups.

As discussed above, for antireflective applications, suitably one ormore of the compounds reacted to form the resin comprise a moiety thatcan function as a chromophore to absorb radiation employed to expose anovercoated photoresist coating layer. For example, a phenyl compoundsuch as styrene or a phenyl acrylate (e.g. benzyl acrylate or benzylmethacrylate) may be polymerized with other monomers to provide a resinparticularly useful in an antireflective composition employed with aphotoresist imaged at sub-200 nm wavelengths such as 193 nm. Similarly,resins to be used in compositions with an overcoated photoresist imagedat sub-300 nm wavelengths or sub-200 nm wavelengths such as 248 nm or193 nm, a naphthyl compound may be polymerized, such as a naphthylcompound containing one or two or more carboxyl substituents e.g.dialkyl particularly di-C₁ _(_) ₆ alkyl naphthalenedicarboxylate.Reactive anthracene compounds also are preferred, e.g. an anthracenecompound having one or more carboxy or ester groups, such as one or moremethyl ester or ethyl ester groups.

For deep UV applications (i.e. the overcoated resist is imaged with deepUV radiation), a polymer of an antireflective composition preferablywill absorb reflections in the deep UV range (typically from about 100to 300 nm). Thus, the polymer preferably contains units that are deep UVchromophores, i.e. units that absorb deep UV radiation. Highlyconjugated moieties are generally suitable chromophores. Aromaticgroups, particularly polycyclic hydrocarbon or heterocyclic units, aretypically preferred deep UV chromophore, e.g. groups having from two tothree to four fused or separate rings with 3 to 8 members in each ringand zero to three N, O or S atoms per ring. Such chromophores includeoptionally substituted phenanthryl, optionally substituted anthracyl,optionally substituted acridine, optionally substituted naphthyl,optionally substituted quinolinyl and ring-substituted quinolinyls suchas hydroxyquinolinyl groups. Optionally substituted anthracenyl groupsare particularly preferred for 248 nm imaging of an overcoated resist.Preferred antireflective composition resins have pendant anthracenegroups. Preferred resins include those of Formula I as disclosed on page4 of European Published Application 813114A2 of the Shipley Company.

Another preferred resin binder comprises optionally substitutedquinolinyl groups or a quinolinyl derivative that has one or more N, Oor S ring atoms such as a hydroxyquinolinyl. The polymer may containother units such as carboxy and/or alkyl ester units pendant from thepolymer backbone. A particularly preferred antireflective compositionresin in an acrylic containing such units, such as resins of formula IIdisclosed on pages 4-5 of European Published Application 813114A2 of theShipley Company.

As discussed above, for imaging at 193 nm, the antireflectivecomposition preferably may contain a resin that has phenyl chromophoreunits. For instance, one suitable antireflective resin for use withphotoresists imaged at 193 nm is a terpolymer consisting of polymerizedunits of styrene, maleic anhydride, and 2-hydroxyethyl methacrylate.

Preferably resins of antireflective compositions of the invention willhave a weight average molecular weight (Mw) of about 1,000 to about10,000,000 daltons, more typically about 5,000 to about 1,000,000daltons, and a number average molecular weight (Mn) of about 500 toabout 1,000,000 daltons. Molecular weights (either Mw or Mn) of thepolymers of the invention are suitably determined by gel permeationchromatography.

While coating composition resins having absorbing chromophores aregenerally preferred, antireflective compositions of the invention maycomprise other resins either as a co-resin or as the sole resin bindercomponent. For example, phenolics, e.g. poly(vinylphenols) and novolaks,may be employed. Such resins are disclosed in the incorporated EuropeanApplication EP 542008 of the Shipley Company. Other resins describedbelow as photoresist resin binders also could be employed in resinbinder components of antireflective compositions of the invention.

The concentration of such a resin component of the coating compositionsof the invention may vary within relatively broad ranges, and in generalthe resin binder is employed in a concentration of from about 50 to 95weight percent of the total of the dry components of the coatingcomposition, more typically from about 60 to 90 weight percent of thetotal dry components (all components except solvent carrier).

Acid or Acid Generator Compound (Optional Component)

Coating compositions of the invention may comprise additional optionalcomponents. Thus, for example, a coating composition may suitablycomprise an added acid source such as an acid or acid generator compoundparticularly a thermal acid generator compound whereby the appliedcoating composition can be hardened such as by thermal treatment priorto application of an overcoated photoresist layer.

However, as discussed above, in preferred aspects, coating compositionsof the invention may be formulated without such an added acid or acidgenerator compound(s). Such compositions free or at least essentiallyfree of any added acid or acid generator compounds may provideperformance benefits, including enhanced shelf life. As referred toherein a composition that is essentially free of added acid or acidgenerator compounds has less than 3, 2 or 1 weight percent of added acidor acid generator compounds based on total weight of the formulatedsolvent-based coating composition. As also referred to herein, an addedacid is distinct from residual acid that may be present in acomposition, such as residual acid entrapped in a resin remaining fromthe resin synthesis.

If an added acid or acid generator compound are employed, a coatingcomposition suitably comprises a thermal acid generator compound (i.e.compound that generates acid upon thermal treatment), such as an ionicor substantially neutral thermal acid generator, e.g. an ammoniumarenesulfonate salt, for catalyzing or promoting crosslinking duringcuring of an antireflective composition coating layer. Typically one ormore thermal acid generators are present in an antireflectivecomposition in a concentration from about 0.1 to 10 percent by weight ofthe total of the dry components of the composition (all componentsexcept solvent carrier), more preferably about 2 percent by weight ofthe total dry components.

Coating compositions of the invention also may contain one or morephotoacid generator compounds typically in addition to another acidsource such as an acid or thermal acid generator compound. In such useof a photoacid generator compound (PAG), the photoacid generator is notused as an acid source for promoting a crosslinking reaction, and thuspreferably the photoacid generator is not substantially activated duringcrosslinking of the coating composition (in the case of a crosslinkingcoating composition). Such use of photoacid generators is disclosed inU.S. Pat. No. 6,261,743 assigned to the Shipley Company. In particular,with respect to coating compositions that are thermally crosslinked, thecoating composition PAG should be substantially stable to the conditionsof the crosslinking reaction so that the PAG can be activated andgenerate acid during subsequent exposure of an overcoated resist layer.Specifically, preferred PAGs do not substantially decompose or otherwisedegrade upon exposure of temperatures of from about 140 or 150 to 190°C. for 5 to 30 or more minutes.

Generally preferred photoacid generators for such use in antireflectivecompositions or other coating of the invention include e.g. onium saltssuch as di(4-tert-butylphenyl)iodonium perfluoroctane sulphonate,halogenated non-ionic photoacid generators such as1,1-bis[p-chlorophenyl]-2,2,2-trichloroethane, and other photoacidgenerators disclosed for use in photoresist compositions. For at leastsome antireflective compositions of the invention, antireflectivecomposition photoacid generators will be preferred that can act assurfactants and congregate near the upper portion of the antireflectivecomposition layer proximate to the antireflective composition/resistcoating layers interface. Thus, for example, such preferred PAGs mayinclude extended aliphatic groups, e.g. substituted or unsubstitutedalkyl or alicyclic groups having 4 or more carbons, preferably 6 to 15or more carbons, or fluorinated groups such as C₁₋₁₅alkyl or C₂₋₁₅alkylalkenyl having one or preferably two or more fluoro substituents.

Formulation of an Underlying Coating Composition

To make a liquid coating composition of the invention, the components ofthe underlying coating composition are dissolved in a suitable solventsuch as, for example, one or more oxyisobutyric acid esters particularlymethyl-2-hydroxyisobutyrate as discussed above, ethyl lactate or one ormore of the glycol ethers such as 2-methoxyethyl ether (diglyme),ethylene glycol monomethyl ether, and propylene glycol monomethyl ether;solvents that have both ether and hydroxy moieties such as methoxybutanol, ethoxy butanol, methoxy propanol, and ethoxy propanol; esterssuch as methyl cellosolve acetate, ethyl cellosolve acetate, propyleneglycol monomethyl ether acetate, dipropylene glycol monomethyl etheracetate and other solvents such as dibasic esters, propylene carbonateand gamma-butyro lactone. A preferred solvent for an antireflectivecoating composition of the invention is methyl-2-hydroxyisobutyrate,optionally blended with anisole. The concentration of the dry componentsin the solvent will depend on several factors such as the method ofapplication. In general, the solids content of an antireflectivecomposition varies from about 0.5 to 20 weight percent of the totalweight of the coating composition, preferably the solids content variesfrom about 2 to 10 weight of the coating composition.

Exemplary Photoresist Systems

A variety of photoresist compositions can be employed with coatingcompositions of the invention, including positive-acting andnegative-acting photoacid-generating compositions. Photoresists usedwith underlying compositions of the invention typically comprise a resinbinder and a photoactive component, typically a photoacid generatorcompound. Preferably the photoresist resin binder has functional groupsthat impart alkaline aqueous developability to the imaged resistcomposition.

Particularly preferred photoresists for use with underlying compositionsof the invention are chemically-amplified resists, particularlypositive-acting chemically-amplified resist compositions, where thephotoactivated acid in the resist layer induces a deprotection-typereaction of one or more composition components to thereby providesolubility differentials between exposed and unexposed regions of theresist coating layer. A number of chemically-amplified resistcompositions have been described, e.g., in U.S. Pat. Nos. 4,968,581;4,883,740; 4,810,613; 4,491,628 and 5,492,793, al of which areincorporated herein by reference for their teaching of making and usingchemically amplified positive-acting resists. Coating compositions ofthe invention are particularly suitably used with positivechemically-amplified photoresists that have acetal groups that undergodeblocking in the presence of a photoacid. Such acetal-based resistshave been described in e.g. U.S. Pat. Nos. 5,929,176 and 6,090,526.

The underlying compositions of the invention also may be used with otherpositive resists, including those that contain resin binders thatcomprise polar functional groups such as hydroxyl or carboxylate and theresin binder is used in a resist composition in an amount sufficient torender the resist developable with an aqueous alkaline solution.Generally preferred resist resin binders are phenolic resins includingphenol aldehyde condensates known in the art as novolak resins, homo andcopolymers or alkenyl phenols and homo and copolymers ofN-hydroxyphenyl-maleimides.

Preferred positive-acting photoresists for use with an underlyingcoating composition of the invention contains an imaging-effectiveamount of photoacid generator compounds and one or more resins that areselected from the group of:

1) a phenolic resin that contains acid-labile groups that can provide achemically amplified positive resist particularly suitable for imagingat 248 nm. Particularly preferred resins of this class include: i)polymers that contain polymerized units of a vinyl phenol and an alkylacrylate, where the polymerized alkyl acrylate units can undergo adeblocking reaction in the presence of photoacid. Exemplary alkylacrylates that can undergo a photoacid-induced deblocking reactioninclude e.g. t-butyl acrylate, t-butyl methacrylate, methyladamantylacrylate, methyl adamantyl methacrylate, and other non-cyclic alkyl andalicyclic acrylates that can undergo a photoacid-induced reaction, suchas polymers in U.S. Pat. Nos. 6,042,997 and 5,492,793; ii) polymers thatcontain polymerized units of a vinyl phenol, an optionally substitutedvinyl phenyl (e.g. styrene) that does not contain a hydroxy or carboxyring substituent, and an alkyl acrylate such as those deblocking groupsdescribed with polymers i) above, such as polymers described in U.S.Pat. No. 6,042,997, incorporated herein by reference; and iii) polymersthat contain repeat units that comprise an acetal or ketal moiety thatwill react with photoacid, and optionally aromatic repeat units such asphenyl or phenolic groups; such polymers have been described in U.S.Pat. Nos. 5,929,176 and 6,090,526.

2) a resin that is substantially or completely free of phenyl or otheraromatic groups that can provide a chemically amplified positive resistparticularly suitable for imaging at sub-200 nm wavelengths such as 193nm. Particularly preferred resins of this class include: i) polymersthat contain polymerized units of a non-aromatic cyclic olefin(endocyclic double bond) such as an optionally substituted norbornene,such as polymers described in U.S. Pat. Nos. 5,843,624, and 6,048,664;ii) polymers that contain alkyl acrylate units such as e.g. t-butylacrylate, t-butyl methacrylate, methyladamantyl acrylate, methyladamantyl methacrylate, and other non-cyclic alkyl and alicyclicacrylates; such polymers have been described in U.S. Pat. No. 6,057,083;European Published Applications EP01008913A1 and EP00930542A1; and U.S.pending patent application Ser. No. 09/143,462, and iii) polymers thatcontain polymerized anhydride units, particularly polymerized maleicanhydride and/or itaconic anhydride units, such as disclosed in EuropeanPublished Application EP01008913A1 and U.S. Pat. No. 6,048,662.

3) a resin that contains repeat units that contain a hetero atom,particularly oxygen and/or sulfur (but other than an anhydride, i.e. theunit does not contain a keto ring atom), and preferable aresubstantially or completely free of any aromatic units. Preferably, theheteroalicyclic unit is fused to the resin backbone, and furtherpreferred is where the resin comprises a fused carbon alicyclic unitsuch as provided by polymerization of a norborene group and/or ananhydride unit such as provided by polymerization of a maleic anhydrideor itaconic anhydride. Such resins are disclosed in PCT/US01/14914.

4) a resin that contains fluorine substitution (fluoropolymer), e.g. asmay be provided by polymerization of tetrafluoroethylene, a fluorinatedaromatic group such as fluoro-styrene compound, and the like. Examplesof such resins are disclosed e.g. in PCUUS99/21912.

Suitable photoacid generators to employ in a positive or negative actingphotoresist overcoated over a coating composition of the inventioninclude imidosulfonates such as compounds of the following formula:

wherein R is camphor, adamantane, alkyl (e.g. C₁₋₁₂ alkyl) andperfluoroalkyl such as perfluoro (e.g. C₁₋₁₂ alkyl) particularlyperfluorooctanesulfonate, perfluorononanesulfonate and the like. Aspecifically preferred PAG isN-[(perfluorooctanesulfonyl)oxy]-5-norbornene-2,3 dicarboximide.

Sulfonate compounds are also suitable PAGs for resists overcoated acoating composition of the invention, particularly sulfonate salts. Twosuitable agents for 193 nm and 248 nm imaging are the following PAGS 1and 2:

Such sulfonate compounds can be prepared as disclosed in European PatentApplication 96118111.2 (publication number 0783136), which details thesynthesis of above PAG 1. Also suitable are the above two iodoniumcompounds complexed with anions other than the above-depictedcamphorsulfonate groups. In particular, preferred anions include thoseof the formula RSO₃— where R is adamantane, alkyl (e.g. C₁₋₁₂ alkyl) andperfluoroalkyl such as perfluoro (e.g. C₁₋₁₂ alkyl) particularlyperfluorooctanesulfonate, perfluorobutanesulfonate and the like.

Other known PAGS also may be employed in photoresist used withunderlying coating compositions.

A preferred optional additive of photoresists overcoated a coatingcomposition of the invention is an added base, particularlytetrabutylammonium hydroxide (TBAH), or tetrabutylammonium lactate,which can enhance resolution of a developed resist relief image. Forresists imaged at 193 nm, a preferred added base is a hindered aminesuch as diazabicyclo undecene or diazabicyclononene. The added base issuitably used in relatively small amounts, e.g. about 0.03 to 5 percentby weight relative to the total solids.

Preferred negative-acting resist compositions for use with an overcoatedcoating composition of the invention comprise a mixture of materialsthat will cure, crosslink or harden upon exposure to acid, and aphotoacid generator.

Particularly preferred negative-acting resist compositions comprise aresin binder such as a phenolic resin, a crosslinker component and aphotoactive component of the invention. Such compositions and the usethereof have been disclosed in European Patent Applications 0164248 and0232972 and in U.S. Pat. No. 5,128,232 to Thackeray et al. Preferredphenolic resins for use as the resin binder component include novolaksand poly(vinylphenol)s such as those discussed above. Preferredcrosslinkers include amine-based materials, including melamine,glycolurils, benzoguanamine-based materials and urea-based materials.Melamine-fobrmaldehyde resins are generally most preferred. Suchcrosslinkers are commercially available, e.g. the melamine resins soldby Cytec Industries under the trade names Cymel 300, 301 and 303.Glycoluril resins are sold by Cytec Industries under trade names Cymel1170, 1171, 1172, Powderlink 1174, and benzoguanamine resins are soldunder the trade names of Cymel 1123 and 1125.

Suitable photoacid generator compounds of resists used with underlyingcompositions of the invention include the onium salts, such as thosedisclosed in U.S. Pat. Nos. 4,442,197, 4,603,10, and 4,624,912, eachincorporated herein by reference; and non-ionic organic photoactivecompounds such as the halogenated photoactive compounds as in U.S. Pat.No. 5,128,232 to Thackeray et al. and sulfonate photoacid generatorsincluding sulfonated esters and sulfonlyoxy ketones. See J. ofPhotopolymer Science and Technology, 4(3):337-340 (1991), for disclosureof suitable sulfonate PAGS, including benzoin tosylate, t-butylphenylalpha-(p-toluenesulfonyloxy)-acetate and t-butylalpha-(p-toluenesulfonyloxy)-acetate. Preferred sulfonate PAGs are alsodisclosed in U.S. Pat. No. 5,344,742 to Sinta et al. The abovecamphorsulfoanate PAGs 1 and 2 are also preferred photoacid generatorsfor resist compositions used with the underlying compositions of theinvention, particularly chemically-amplified resists of the invention.

Photoresists for use with an antireflective composition of the inventionalso may contain other materials. For example, other optional additivesinclude actinic and contrast dyes, anti-striation agents, plasticizers,speed enhancers, etc. Such optional additives typically will be presentin minor concentration in a photoresist composition except for fillersand dyes which may be present in relatively large concentrations suchas, e.g., in amounts of from about 5 to 50 percent by weight of thetotal weight of a resist's dry components.

Lithographic Processing

In use, a coating composition of the invention is applied as a coatinglayer to a substrate by any of a variety of methods such as spincoating. The coating composition in general is applied on a substratewith a dried layer thickness of between about 0.02 and 0.5 m, preferablya dried layer thickness of between about 0.04 and 0.20 μm. The substrateis suitably any substrate used in processes involving photoresists. Forexample, the substrate can be silicon, silicon dioxide oraluminum-aluminum oxide microelectronic wafers. Gallium arsenide,silicon carbide, ceramic, quartz or copper substrates may also beemployed. Substrates for liquid crystal display or other flat paneldisplay applications are also suitably employed, for example glasssubstrates, indium tin oxide coated substrates and the like. Substratesfor optical and optical-electronic devices (e.g. waveguides) also can beemployed.

Preferably the applied coating layer is cured before a photoresistcomposition is applied over the antireflective composition. Cureconditions will vary with the components of the coating composition.Typical cure conditions are from about 150° C. to 250° C. for about 0.5to 5 minutes. Cure conditions preferably render the coating compositioncoating layer substantially insoluble to the photoresist solvent as wellas an alkaline aqueous developer solution.

After such curing, a photoresist is applied above the surface of the topcoating composition. As with application of the bottom coatingcomposition layer(s), the overcoated photoresist can be applied by anystandard means such as by spinning, dipping, meniscus or roller coating.Following application, the photoresist coating layer is typically driedby heating to remove solvent preferably until the resist layer is tackfree. Optimally, essentially no intermixing of the bottom compositionlayer and overcoated photoresist layer should occur.

The resist layer is then imaged with activating radiation through a maskin a conventional manner. The exposure energy is sufficient toeffectively activate the photoactive component of the resist system toproduce a patterned image in the resist coating layer. Typically, theexposure energy ranges from about 3 to 300 mJ/cm² and depending in partupon the exposure tool and the particular resist and resist processingthat is employed. The exposed resist layer may be subjected to apost-exposure bake if desired to create or enhance solubilitydifferences between exposed and unexposed regions of a coating layer.For example, negative acid-hardening photoresists typically requirepost-exposure heating to induce the acid-promoted crosslinking reaction,and many chemically amplified positive-acting resists requirepost-exposure heating to induce an acid-promoted deprotection reaction.Typically post-exposure bake conditions include temperatures of about50° C. or greater, more specifically a temperature in the range of fromabout 50° C. to about 160° C.

The photoresist layer also may be exposed in an immersion lithographysystem, i.e. where the space between the exposure tool (particularly theprojection lens) and the photoresist coated substrate is occupied by animmersion fluid, such as water or water mixed with one or more additivessuch as cesium sulfate which can provide a fluid of enhanced refractiveindex. Preferably the immersion fluid (e.g. water) has been treated toavoid bubbles, e.g. water can be degassed to avoid nanobubbles.

References herein to “immersion exposing” or other similar termindicates that exposure is conducted with such a fluid layer (e.g. wateror water with additives) interposed between an exposure tool and thecoated photoresist composition layer.

The exposed resist coating layer is then developed, preferably with anaqueous based developer such as an alkali exemplified by tetramethylammonium hydroxide, sodium hydroxide, potassium hydroxide, sodiumcarbonate, sodium bicarbonate, sodium silicate, sodium metasilicate,aqueous ammonia or the like. Alternatively, organic developers can beused. In general, development is in accordance with art recognizedprocedures. Following development, a final bake of an acid-hardeningphotoresist is often employed at temperatures of from about 100° C. toabout 150° C. for several minutes to further cure the developed exposedcoating layer areas.

The developed substrate may then be selectively processed on thosesubstrate areas bared of photoresist, for example, chemically etching orplating substrate areas bared of photoresist in accordance withprocedures well known in the art. Suitable etchants include ahydrofluoric acid etching solution and a plasma gas etch such as anoxygen plasma etch.

The following non-limiting examples are illustrative of the invention.

EXAMPLES 1-10—RESIN SYNTHESES

General Procedures for Anhydride-Polymer Synthesis as Employed inExamples 1-10

The reaction set up consisted of a three-neck, round-bottom flask ofappropriate size containing a magnetic stir bar, and fitted with atemperature probe, dropping funnel, water-cooled condenser, dispenseline attached to a syringe fitted to a syringe pump, and a nitrogeninlet (blanket). The temperature was controlled using an oil bath intandem with a hotplate/stirplate. Initially charged to the flask was amonomer and solvent. To the dropping funnel was added the initiatorsolution. A feed solution containing monomers and solvent was placed inthe syringe and affixed to the syringe pump. The mixture in the flaskwas heated to approximately 70° C. before adding the initiator solution.The monomer solution in the syringe was then delivered to the reactionmixture at a continuous rate over a period of 3-3.5 hours. When theaddition was complete, the reaction mixture was allowed to continuestirring at 70° C. for an additional 30 minutes. The reaction was thenthermally quenched by removing the heat source, diluting with solvent,and allowing the mixture to cool to room temperature.

GPC was determined relative to polystyrene standards with RI detection(495 dalton cutoff) and THF as elution solvent. Some polymers in theexamples below were further characterized for either optical density(OD). The polymers were spin-coated from solution onto both silicon andquartz wafers. The thickness of the films on silicon was measured. Theabsorptivity of the films on quartz was determined by UVspectrophotometry. The absorptivity was measured against a blank quartzwafer. From the thickness and absorptivity measurements, the OD wascalculated at 13 nm.

Monomers:

3,4-Dihydro-2H-pyran (DHP)

Maleic Anhydride (MA)

2-Hydroxyethyl Methacrylate (HEMA)

t-Butyl Methacrylate (tBMA)

3,5-Bis(hexafluoro-2-hydroxy-2-propyl)cyclohexyl Methacrylate (HFACHM)

Pentafluoroethyl Acrylate (PFA)

Methyl Methacrylate (MMA)

Styrene

Benzyl Methacrylate (BMA)

Initiators:

V-601

Vazo-67

Solvents:

Tetrahydrofuran (THF)

Isopropanol (IPA)

Methyl, 2-Hydroxyisobutyrate (HBM)

In the following Examples 1-10, the above anhydride resin synthesisprocedure was employed with reagents as specified in the particularexample. The above-listed reagents were employed as designated with thespecified abbreviations. The molar ratios of the repeat units of theproduced resin is specified in the Example hearing, thus in Example, theproduced resin 35/35/30 DHP/MA/HEMA had 35 mole percent of polymerized3,4-dihydro-2H-pyran, 35 mole percent maleic anhydride and 30 molepercent 2-hydroxyethyl methacrylate.

EXAMPLE 1—35/35/30 DHP/MA/HEMA

Initial contents to reaction flask: DHP 16.2 g (193 mmol), and THF 31.7g

To dropping funnel: V-601 2.53 g, and THF 3.71 g

Added from syringe: MA 18.9 g (193 mmol), HEMA 21.5 g (165 mmol), andTHE 22 g Diluent: THF 66 g

Following the reaction, the solution was precipitated into IPA, washedwith IPA, filtered, air-dried, and then dried in vacuo at 40 C overnightto yield 38 g (67%) of a dry powder.

Mw=18,817, Mn=5347

EXAMPLE 2—45/50/5 MA/HEMA/TBMA

Initial contents to reaction flask: MA 23.7 g (242 mmol), and HBM 44 g

To dropping funnel: Vazo-67 2.6 g, and HBM 4.8 g

Added from syringe: HEMA 34.9 g (268 mmol), tBMA 3.81 g (26.8 mmol), andHBM 46 g Diluent: HBM 490 g

Mw=27,711, Mn=5567

EXAMPLE 3—45/50/5 MA/HEMA/TBMA

Initial contents to the reaction flask: MA 23.7 g (242 mmol), and HIM132 g

To dropping funnel: Vazo-67 2.6 g, and HBM 14.5 g

Added from syringe: HEMA 34.9 g (268 mmol), tBMA 3.81 (26.8 mmol), andHBM 48.5 g Diluent: HBM 390 g

Mw=19,822, Mn=7992

EXAMPLE 4—50/50 MA/HFACHM

Initial contents to the reaction flask: MA 4.1 g (42 mmol), and HBM 23 g

To dropping funnel: Vazo-67 1.0 g, and HBM 6 g

Added from syringe: HFACHM 20.9 g (42 mmol), and HBM 49 g Diluent: HBM156 g

Mw=36,741, Mn=12,469

EXAMPLE 5—50/30/20 MA/PFA/HEMA

Initial contents to reaction flask: MA 11.2 g (114 mmol), and HBM 62.5 g

To dropping funnel: Vazo-67 1.3 g, and HBM 7.3 g

Added from syringe: PFA 14.0 g (69 mmol), HEMA 6.0 g (46 mmol), and HBM27.7 g Diluent: HBM 182 g

Mw=23,877, Mn=8322

EXAMPLE 6—45/30/25 MA/MMA/HEMA

Initial contents to reaction flask: MA 25.6 g (261 mmol), and HBM 144 g

To dropping funnel: Vazo-67 2.6 g, and HBM 14.5 g

Added from syringe: HEMA 19.0 g (146 mmol), MMA 17.6 g (176 mmol), andHBM 36.5 g Diluent: HBM 390 g

Mw=33,843, Mn=13,973

EXAMPLE 7—45/45/10 MA/MMA/HEMA

Initial contents to reaction flask: MA 26.95 g (275 mmol), and HBM (150g)

To the dropping funnel: Vazo-67 2.6 g, and HBM 14.5 g

Added from syringe: HEMA 7.95 g (61 mmol), MMA 27.5 g (275 mmol), andHBM 30.5 g Diluent: HBM 390 g

Mw=33,588, Mn=13,893

EXAMPLE 8—20/35/45 Styrene/HEMA/MA

Initial contents to reaction flask: MA 24.9 g (254 mmol), and HBM 141 g

To the dropping funnel: Vazo-67 2.6 g, and HBM 15 g

Added from syringe: HEMA 25.7 g (198 mmol), styrene 11.8 g (113 mmol),and HBM 39 g Diluent: HBM 390 g

Mw=46,623, Mn=14,479, OD=8.51 (193 nm)

EXAMPLE 9—10/45/45 Styrene/HEMA/MA

Initial contents to reaction flask: MA 24.3 g (248 mmol), and HBM 138.5g

To the dropping funnel: Vazo-67 2.6 g, and HBM 14.5 g

Added from syringe: HEMA 32.3 g (248 mmol), styrene 5.7 g (55 mmol), andHBM 42 g Diluent: HBM 390 g

Mw=34,778, Mn=12,993, OD=4.96 (193 nm)

EXAMPLE 10—45/30/25 MA/HEMA/BMA

Initial contents to reaction flask: MA 21.5 g (219 mmol), and HBM 125 g

To dropping funnel: Vazo-67 3 g, and HBM 15 g

Added from syringe: HEMA 19.0 g (146 mmol), BMA 21.5 g (122 mmol), andHBM 58 g Diluent: HBM 390 g

EXAMPLES 11-22 (Polymer Solutions)

The examples in the below Tables 1 and 2 contain only polymer and HBMsolvent. No other additives were used. Examples 11-15 contain only onepolymer as indicated in Table 1. For Examples 16-22, three uniquepolymers are blended at the amounts indicated in Table 2, and are asfollows:

MA polymer=45/45/10 MA/MMA/HEMA (Mw=33,588)

Polyester=Poly(1,4-dimethylterephthalate-co-1,3,5-tris(2-hydroxyethyl)cyanuric acid (Mw-3000)

Acrylate=40/60 HEMA/MMA (Mw=11,257)

General Procedures for Coating Wafers

For all wafers (silicon or quartz) spin-coated with the formulatedsamples, the spin time was 30 s, at 2000 rpm. Then the wafers were bakedon a hotplate for 60 s at the temperature indicated in the tables below.The thickness of the films on silicon wafers was measured byellipsometry (nanospeck).

General Procedures for Measuring Solvent Resistance

Each sample solution tested for solvent resistance was spin-coated ontoa silicon wafer. The thickness of the wafer was measured usingellipsometry (nanospeck). HBM poured over the surface of the wafer andallowed to sit for 60 seconds. The wafer was then spun dry at 4000 rpmfor 60 seconds and the thickness was measured again.

TABLE 1 Change in Film Thickness Following Thermal Cure and SolventStrip Example Polymer Mw 90° C. 115° C. 150° C. 180° C. 215° C. 1145/50/5 27,711 −7.4% −0.1% 1.2% 0% −0.1% MA/HEMA/tBMA 12 45/50/5 19,822— — −1.9% 0%  0.3% MA/HEMA/tBMA 13 35/35/30 23,151 — — — —    0%DHP/MA/HEMA 14 20/35/45 46,623 — — — —  0.2% Styrene/HEMA/MA 15 10/45/4537,778 — — — — −0.3% Styrene/HEMA/MA

TABLE 2 Film Thickness Remaining After Thermal Cure and Solvent Strip MAExample Polymer Polyester Acrylate 120° C. 150° C. 180° C. 210° C. 240°C. 16 25 75 — 0.4%  0% 3.2% 1.6% 2.1% 17 50 50 — 2.7% 3.0% 0.8% 78.9%97.6% 18 75 25 — 0.1% 4.9% 12.7% 86.4% 96.4% 19 25 — 75 1.5% 3.3% 28.6%40.1% 48.2% 20 50 — 50 4.1% 8.4% 50.7% 67.7% 77.8% 21 75 — 25 35.6%71.8%  87.4% 91.1% 94.0% 22 100 — — 68.9% 88.2%  95.0% 94.6% 95.2%

EXAMPLES 22-25 (Additional Coating Composition Processing)

Examples 22-25 in Table 3 below demonstrate polymer insolubility to atypical resist solvent and to a developer after a thermal treatment.Poly(styrene-co-maleic anhydride), cumene terminated with a typical Mnof about 1,600 and poly(styrene-co-allyl alcohol) with a typical Mn ofabout 1,200 (both purchased from Aldrich Chemical Company) wereco-dissolved in propylene glycol monomethylether acetate to form several10 weight percent solutions containing different amounts of eachpolymer. The solutions were filtered through a 0.2 μm filter and eachspin coated on a set of two six inch wafers using a DNS track at 3000rpm. The coated wafers were then heated for 60 seconds to the indicatedtemperature using a hot plate to induce cross-linking. One of the waferof each set was covered with a puddle of ethyl lactate, EL, for 60seconds and then spun dry. The second wafer was immersed in a bath of0.26N tetramentylammonium hydroxide, TMAH, solution for 60 secondsfollowed by a water rinse and a nitrogen blow dry. Film thickness (FT)was measured after the bake and after the solvent or developer exposureusing a Thermowave instrument.

TABLE 3 % Styrene- co-allyl Bake Initial EL, TMAH, % Loss % LossExamples alcohol □ C. FT Å 60 sec. 60 sec to EL to TMAH Example 22 50200 2117 2097 1 200 2126 2129 −0.13 Example 23 25 200 2132 2127 0.22 2002135 2139 −0.2 Example 24 200 2182 2178 0.2 20 200 2179 2181 −0.1DPH-MA- HEMA Example 25 225 8278 8236 0.5 100% 225 8365 8453 −1.05

EXAMPLE 26—LITHOGRAPHIC PROCESSING

This example shows use of an underlying coating composition of theinvention as an underlayer/anti reflective layer to a 193 nm resist.

Process Conditions

1) Underlayer: 215 nm coating layer of Example 26 cured at 200° C./60seconds on a vacuum hotplate;

2) Photoresist: 260 nm coating layer of an acrylate-based 193 nmphotoresist soft-baked at 120° C./60 seconds on a vacuum hotplate;

3) Exposure: the applied photoresist layer was exposed to patterned 193nm radiation;

4) Post-Exposure Bake: 120° C./60 seconds;

5) Development: the latent image was developed with 0.26N aqueousalkaline developer to provide a photoresist relief image.

What is claimed is:
 1. A coated substrate comprising: an organic coatingcomposition layer comprising 1) a first resin that comprises anhydridegroup and 2) a second resin that is distinct from the first resin andcomprises hydroxyl groups, wherein the first and second resins areacrylate resins; a photoresist composition layer above the organiccoating composition layer.
 2. A substrate of claim 1 wherein the organiccoating composition is free of an amine-containing crosslinker componentand an epoxy crosslinker component.
 3. A substrate of claim 1 whereinthe organic coating composition is free of an amine-containingcrosslinker component.
 4. A substrate of claim 1 wherein the organiccoating composition is free of an epoxy crosslinker component.
 5. Asubstrate of claim 1 wherein the first resin or second resin comprisesone or more phenyl groups.
 6. A substrate of claim 1 wherein the organiccoating composition layer is at least essentially free of an acid oracid generator compound.
 7. A substrate of claim 1 wherein thephotoresist composition layer comprises one or more resin withphotoacid-labile groups and is substantially free of aromatic groups. 8.A substrate of claim 1 wherein the organic coating composition is anantireflective coating composition.
 9. An antireflective composition foruse with an overcoated photoresist layer, the antireflective coatingcomposition comprising 1) a first resin that comprises anhydride groupand 2) a second resin that is distinct from the first resin andcomprises hydroxyl groups, wherein the first and second resins areacrylate.
 10. An antireflective coating composition of claim 9 whereinthe antireflective composition is free of an amine-containingcrosslinker component and an epoxy crosslinker component.
 11. Anantireflective coating composition of claim 9 wherein the antireflectivecomposition is free of an amine-containing crosslinker component.
 12. Anantireflective composition of claim 9 wherein the antireflectivecomposition is free of an epoxy crosslinker component.
 13. Anantireflective composition of claim 9 wherein the first resin or secondresin comprises one or more phenyl groups.
 14. An antireflectivecomposition of claim 9 wherein the antireflective composition is atleast essentially free of an acid or acid generator compound.
 15. Acoating composition, comprising 1) a first resin that comprisesanhydride group and 2) a second resin that is distinct from the firstresin and comprises hydroxyl groups, wherein the first and second resinsare acrylate resins.